Dirty Rotten Scoundrels (1988)

Steve Martin, Michael Caine

Wealthy native Brit Lawrence Jamieson, living in Beaumont-sur-Mer on the French Riviera, earns most of his money through big cons on wealthy unsuspecting women. With the help of his associates, corrupt Police Inspector Andre, who provides him most of his intel, and his butler Arthur, he pulls scams such as pretending to be a foreign deposed Prince who needs money to finance a secret war to liberate his people. Beaumont-sur-Mer, and thus his world, is invaded by brash American Freddy Benson, another con man whose targets are also wealthy unsuspecting women. Lawrence believes Freddy is the Jackal, a con man whose true identity is unknown, but who is known to be working his way through Europe. While Lawrence works on thousands of dollars per scam, Freddy works only on tens or if he is lucky hundreds of dollars. Lawrence's efforts to get Freddy out of his territory are unsuccessful, so when Freddy figures out that Lawrence is a con man like he is, he decides to blackmail Lawrence to work under him to learn the art of the sophisticated and thus earn more lucrative con. Eventually, Lawrence and Freddy have a difference in how to operate their joint cons, so they issue each other an ultimatum: the person who is able to con a mark out of fifty thousand dollars first will get the French Riviera as their territory, with the other having to leave forever. Who they choose is naive and slightly bumbling American "soap Queen" Janet Colgate, who has just arrived in the area. The nature of how each tries to get the fifty thousand dollars from Janet changes over time, each needing to play off the other's con. But their focus may change with more information learned about the situation, as well as some external factors they did not anticipate.

From IMDB:

Hilarious!
Everything clicks in this laugh-out-loud gem. Steve Martin and Michael Caine are in top form as Freddy Benson and Lawrence Jamieson, two con men who agree that this town (on the French Mediterranean coast) ain't big enough for the both of them. To solve the problem, they agree upon a solution - the first man to swindle $50,000 from a naive young woman gets to stay. The competition brings out the very best of their very worst, with Martin posing as a paraplegic and Caine as a psychiatrist eager to help convince him it's all in his head. Glenne Headly, as the target of the cons, deserves special mention for her brilliant performance.

One of the strongest assets of "Dirty Rotten Scoundrels" is that the story is interesting enough, with its various twists and turns, that it would work great even without being funny. The laughs - and there are many of them - are a sort of gut-hurting bonus. The scene in which Caine tests the nerves in Martin's legs must rank as one of the most uproarious in film history. This one from director Frank Oz (certainly no slouch in the comedy department) is not to be missed.

https://www2.zoechip.com/movie/dirty-rotten-scoundrels-16956